New research from the Monell Center reveals that the olfactory marker protein (OMP), a molecule found in the cells that detects odor molecules, plays an important role in regulation of speed and transmission of odor information being sent from the nose to the brain after being received by the olfactory receptor neurons (ORN).

“At any one time, thousands of different odor molecules arrive at the smell receptors in our noses to provide detailed information about the surrounding world. OMP helps the smell receptor cells filter this vast amount of information so that animals can respond appropriately,” said Johannes Reisert, Monell cellular physiologist.

The findings solve a 30-year-old mystery regarding the function of OMP and increases understanding of how the olfactory system integrates information to transmit accurate data about odors and the messages they contain

The Study

For the study, researchers used mice that were engineered to be missing this protein marker (OMP) in order to pinpoint the role OMP has with the system. It was found that OMP is similar to a filter, allowing the brain to identify individual scents without being overloaded with numerous pieces of information.

Reisert discovered that mice that did not have the OMP had similar high levels of cAMP (a molecule inside the olfactory receptor neurons that is activated when an odor is detected so the action potential can rise to the critical threshold, found in an earlier study) regardless of which olfactory receptor was expressed. In normal mice, the levels of cAMP varied in ORN.

“What this tells us is that OMP dampens cAMP ’noise’ to allow the olfactory system to differentiate between ORs and to allow faithful transmission of odor information to the brain,” added Reisert.

Further Results

Other results of the study displayed that mice without OMP weren’t as able to organize odor information over time and were especially less responsive to odors that were present for shorter amounts of time.

“Understanding how OMP and the ORs dictate ORN responses will help drive the direction of future studies to understand how ORNs contribute to our ability to experience and respond to our olfactory world,” said Michele Dibattista, Monell neuroscientist and an author to the study’s paper.